Programa de Pós-Graduação em Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil.
Metab Brain Dis. 2012 Dec;27(4):541-9. doi: 10.1007/s11011-012-9321-y. Epub 2012 Jun 7.
Hyperprolinemia is an inherited disorder of proline metabolism and hyperprolinemic patients can present neurological manifestations, such as seizures cognitive dysfunctions, and psychotic disorders. However, the underlying mechanisms of these symptoms are still unclear. Since adenine nucleotides play crucial roles in neurotransmission and neuromodulation, we evaluated the in vivo and in vitro effects of proline on ectonucleotidase activities and gene expression in zebrafish brain. For the in vivo studies, animals were exposed at two proline concentrations (1.5 and 3.0 mM) during 1 h or 7 days (short- or long-term treatments, respectively). For the in vitro assays, different proline concentrations (ranging from 3.0 to 1000 μM) were tested. Short-term proline exposure did not promote significant changes on the ectonucleotidase activities and gene expression. Long-term proline exposure significantly increased ATP catabolism in both concentrations tested (14 % and 22 %, respectively), whereas ADP and AMP hydrolysis were increased only at 3.0 mM proline (21 % and 17 %, respectively) when compared to control. Moreover, the relative gene expression of enpd3 increased in both treated groups after long-term proline, whereas enptd1 increased only at 3.0 mM proline. Proline in vitro did not promote significant changes on ectonucleotidase activities. Altogether, these data indicate that the enzymes responsible for the control of extracellular nucleotides levels might be altered after proline exposure in zebrafish, contributing to better understand the pathophysiology of this disease. Moreover, such findings might facilitate the use of the zebrafish as a complementary vertebrate model for studying inborn errors of amino acid metabolism.
高脯氨酸血症是一种脯氨酸代谢的遗传性疾病，高脯氨酸血症患者可出现神经表现，如癫痫、认知功能障碍和精神障碍。然而，这些症状的潜在机制尚不清楚。由于腺嘌呤核苷酸在神经传递和神经调节中发挥着关键作用，我们评估了脯氨酸对斑马鱼大脑中外切核苷酸酶活性和基因表达的体内和体外影响。在体内研究中，动物在两种脯氨酸浓度（1.5 和 3.0 mM）下暴露 1 小时或 7 天（分别为短期和长期处理）。在体外测定中，测试了不同的脯氨酸浓度（范围从 3.0 到 1000 μM）。短期脯氨酸暴露不会引起外切核苷酸酶活性和基因表达的显著变化。长期脯氨酸暴露在两种测试浓度下均显著增加 ATP 分解代谢（分别增加 14%和 22%），而 ADP 和 AMP 水解仅在 3.0 mM 脯氨酸时增加（分别增加 21%和 17%）与对照组相比。此外，enpd3 的相对基因表达在长期脯氨酸处理的两组中均增加，而 enptd1 仅在 3.0 mM 脯氨酸时增加。脯氨酸在体外对外切核苷酸酶活性没有显著影响。总之，这些数据表明，在斑马鱼中暴露于脯氨酸后，可能会改变负责控制细胞外核苷酸水平的酶，有助于更好地理解这种疾病的病理生理学。此外，这些发现可能有助于利用斑马鱼作为研究氨基酸代谢先天错误的补充脊椎动物模型。
